JP4612540B2 - Nuclear fuel assembly - Google Patents

Description

  The present invention relates to a nuclear fuel assembly of a small nuclear reactor using a coolant such as a liquid metal, and in particular, P / D (P: fuel pin pitch, D: fuel pin outer diameter) is 1 in a fuel pin bundle having a triangular pitch arrangement. The present invention relates to a nuclear fuel assembly in which a corrugated grid is configured in a repetitive stage in order to reduce pressure loss when it is smaller than 1.

  In general, in a small nuclear reactor using a coolant such as liquid metal, a nuclear fuel assembly is supported by a core while being mounted on a support member. In such a nuclear fuel assembly, a plurality of fuel pins are held in the radial interval by a grid, and the holding between the axial grids is held by a tie rod or the like. As for the grid, a Rhombus grid is particularly used as a low-pressure loss grid when the fuel pin bundle P / D (P: fuel pin pitch, D: fuel pin outer diameter) is generally larger than 1.2.

  97 to 99 show the configuration of a conventional nuclear fuel assembly. 97 is a longitudinal sectional view showing the overall configuration of the nuclear fuel assembly, and FIG. 98 is a sectional view taken along line XX in FIG. As shown in these drawings, the plurality of fuel pins 101 are arranged in the vertical direction while being pinned by a grid 102 and are stored in a trumpet tube 103.

  The lower part of the fuel pin 101 is fixed to the lower pin support plate 105, and the upper part is fixed to the upper pin support plate 106. A coolant such as liquid metal flows from the coolant inlet 108 of the entrance nozzle 104 provided at the lower portion of the wrapper tube 103, rises between the fuel pins 101, and passes through the handling head 107 provided at the upper portion of the wrapper tube 103. It flows out from the coolant outlet 109.

In the nuclear fuel assembly configured as described above, as shown in FIG. 99, a grid frame 112 and a Rhombus grid 110 including a plurality of Rhombus elements 111 are used as a low-pressure loss grid. Conventionally, for a nuclear reactor using a coolant such as a liquid metal, a technique for increasing the reactivity control capability has been developed (see, for example, Patent Document 1).
JP-A-6-51082

  In the above-mentioned conventional nuclear fuel assembly, when P / D is approximately 1.2 or more, a Rhombus grid 110 as shown in FIG. 99 is established. However, in a small nuclear reactor, a dense type fuel is used to increase combustion efficiency. A pin 101 array is required. In particular, the target is a pin diameter D = 14 mm of about P / D = 1.08. In this case, the Rhombus grid 110 is not established because the establishment limit P / D> 1.154 of the Rhombus grid 110 is smaller. Further, the conventional honeycomb or ring type grid has a problem that the pressure loss is large.

  The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to provide a low pressure loss and dense fuel assembly.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a nuclear fuel assembly loaded in a reactor core using a liquid metal as a coolant , on a cross section perpendicular to the axial direction of the nuclear fuel assembly, It has a corrugated shape that is curved in alternate directions for each predetermined distance, and has a plurality of corrugated elements for storing and holding a plurality of fuel pins at equal intervals in a trumpet tube, and two grooves, A connecting plate for meshing the corrugated elements to connect the corrugated elements; a plurality of grids in which the corrugated elements and the connecting plates are fixed to a grid frame; an entrance nozzle; and a handling head. An element provides a nuclear fuel assembly, wherein the fuel pin is supported by two point contacts or two line contacts on a horizontal cross section of the nuclear fuel assembly.

  As described above, the corrugated element and the connecting plate are fixed to the grid frame as a grid for storing and holding a plurality of fuel pins at equal intervals in the trumpet, and P / D = 1.08 and D = 14 mm (P: In the case of fuel pin pitch, D: fuel pin outer diameter), and element thickness t0.2 mm, the blockage ratio ε = 0.10 of the corrugated grid can be achieved with the bare bundle portion channel area of the fuel pin portion being 1. An effective means for reducing the pressure loss is to reduce the blocking rate. Incidentally, at the same P / D, D and t, the closing rate ε = 0.17 in the honeycomb grid and the closing rate ε = 0.23 in the ring grid. For this reason, the pressure loss of the grid can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

In the invention according to claim 2, it has a corrugated shape that is curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly, and a plurality of fuel pins are arranged at equal intervals in the trumpet. A plurality of corrugated elements to be stored and held, a connection plate that has two grooves, meshes the corrugated elements in the grooves and connects the corrugated elements, and the corrugated elements and the connection plate are grid frames. A multi-stage grid in which two fixed grids obtained by rotating the direction of the corrugated element by 60 ° , an entrance nozzle, and a handling head are provided, and each of the corrugated elements includes the nuclear fuel. It is possible to provide a nuclear fuel assembly characterized in that the fuel pin is supported by two point contacts or two line contacts on a horizontal section of the assembly.

According to a third aspect of the present invention, the cross section perpendicular to the axial direction of the nuclear fuel assembly has a corrugated shape curved in alternate directions at predetermined distances, and a plurality of fuel pins are arranged at equal intervals in the trumpet. A plurality of corrugated elements to be stored and held, a connection plate that has two grooves, meshes the corrugated elements in the grooves and connects the corrugated elements, and the corrugated elements and the connection plate are grid frames. The fixed grid is configured as a multi-stage grid with spacing in the axial direction and the grid waveform elements adjacent in the axial direction rotated in different directions, the entrance nozzle, a handling head, Each of the corrugated elements supports the fuel pin with two point contacts or two line contacts on a horizontal cross section of the nuclear fuel assembly, and is intended to reduce pressure loss with the nuclear fuel assembly. It is possible to improve the structural strength.

In a fourth aspect of the invention, the cross section perpendicular to the axial direction of the nuclear fuel assembly has a chevron shape bent in alternate directions at predetermined distances, and a plurality of fuel pins are stored in the trumpet at equal intervals. A plurality of chevron elements to be held, two grooves, a connecting plate for connecting the chevron elements by engaging the chevron elements in the grooves, and fixing the chevron elements and the connecting plate to the grid frame A plurality of grids, an entrance nozzle, and a handling head, and each of the chevron elements supports the fuel pin with two point contacts or two line contacts on a horizontal section of the nuclear fuel assembly. A featured nuclear fuel assembly can be provided.

The invention according to claim 5 has a corrugated shape curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly, and a plurality of fuel pins are equidistantly arranged in the trumpet. A plurality of corrugated elements to be stored and held ; a notch portion provided on an axially horizontal surface of the nuclear fuel assembly of the corrugated element; and two grooves, wherein the corrugated elements are respectively disposed in the grooves. A connection plate that meshes and connects the wave elements, a plurality of grids that fix the wavefront wave element and the connection plate to a grid frame, an entrance nozzle, and a handling head, each wave element, The fuel pin is supported by two point contacts or two line contacts on the horizontal cross section of the nuclear fuel assembly, and the pressure loss of the grid can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

The invention according to claim 6 has a corrugated shape curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly, and a plurality of fuel pins are equidistantly arranged in the trumpet. A part of the plate to be stored and held has a plurality of corrugated elements provided with continuous protrusions along the horizontal direction and two grooves, and the corrugated elements are respectively engaged with the grooves to connect the corrugated elements. A connection plate, a plurality of grids in which the corrugated element and the connection plate are fixed to a grid frame, an entrance nozzle, and a handling head, each corrugated element on a horizontal section of the nuclear fuel assembly It is possible to provide a nuclear fuel assembly characterized in that the fuel pin is supported by two point contacts or two line contacts.

The invention according to claim 7 has a corrugated shape curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly, and a plurality of fuel pins are equidistantly arranged in the trumpet. A plurality of corrugated elements to be stored and held, a connection plate that has two grooves, meshes the corrugated elements in the grooves and connects the corrugated elements, and the corrugated elements and the connection plate are grid frames. A plurality of fixed grids, an entrance nozzle, and a handling head, each of the corrugated element and the connecting plate is machined into a triangular edge at each of the corrugated elements, and each corrugated element is a horizontal section of the nuclear fuel assembly. The nuclear fuel assembly is characterized in that the fuel pin is supported by two point contacts or two line contacts , and the pressure loss of the grid can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.
In the invention according to claim 8, the pitch P of the fuel pins and the outer diameter D of the fuel pins are 1 <P / D <1.154, and the pressure loss of the grid can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

  In the above-described conventional triangular pitch array nuclear fuel assembly, a Rhombus grid was established when the P / D was approximately 1.2 or more. However, in a small nuclear reactor (4S reactor, etc.), a dense type was used to increase combustion efficiency. A fuel pin 101 array is required. In particular, the target is a pin diameter D = 14 mm of about P / D = 1.08. In this case, the rhombus grid is not established because the establishment limit P / D> 1.154 of the rhombus grid is smaller. Further, the conventional honeycomb or ring type grid has a problem that the pressure loss is large.

  The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to obtain a low-pressure loss grid spacer. In order to achieve the above object, in the nuclear fuel assembly of the present invention, according to the first aspect of the present invention, the corrugated element and the connecting plate are used as a grid frame as a grid for storing and holding a plurality of fuel pins at equal intervals in the trumpet. With a fixed structure, P / D = 1.08, D = 14 mm (P: fuel pin pitch, D: fuel pin outer diameter), and element bundle t0.2 mm, the flow area of the bare bundle portion of the fuel pin portion is 1. The blockage rate ε = 0.10 of the waveform grid can be achieved. An effective means for reducing the pressure loss is to reduce the blocking rate. Incidentally, at the same P / D, D and t, the closing rate ε = 0.17 in the honeycomb grid and the closing rate ε = 0.23 in the ring grid. For this reason, the pressure loss of the grid can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

  Moreover, in another claim, there exists an effect which suppresses a deformation | transformation of the outer periphery pin with a large thermal curve by a partial grid.

  Further, the peripheral obstruction structure flow effect can be prevented by the peripheral obstruction structure, and there is an effect of improving thermal efficiency and improving soundness.

Hereinafter, an embodiment of a nuclear fuel assembly according to the present invention with reference to FIG. 1-96. Since the overall configuration is substantially the same as that shown in FIGS. 97 to 99 , this figure is also used for the description of the following embodiments.

[First Embodiment (FIGS. 1 to 12)]
FIG. 1 shows a corrugated grid 1 for storing and holding a plurality of fuel pins 101 at equal intervals in a trumpet tube. The corrugated grid 1 has a structure in which the corrugated element 2 and the connection plate 4 are welded and fixed to the grid frame 112, P / D = 1.08, D = 14 mm (P: fuel pin pitch, D: fuel pin outer diameter), element thickness When the thickness t is 0.2 mm, the flow rate of the bare bundle portion of the fuel pin portion is set to 1, and the blockage rate ε = 0.10 of the corrugated grid 1 is achieved.

  An effective means for reducing the pressure loss is to reduce the blocking rate. Incidentally, at the same P / D, D, and t, the honeycomb grid has a blocking rate ε = 0.17, and the ring grid has a blocking rate ε = 0.23. For this reason, the pressure loss of the grid can be reduced. Although FIG. 1 shows a holding configuration in which the tie rod 5 is applied to hold the corrugated grid 1 in the axial direction, other holding configurations can be applied.

  In FIG. 1, 37 fuel pins 101 are shown, but the number of fuel pins 101 is not particularly limited.

  FIG. 2A shows an enlarged waveform grid 1. As shown in FIG. 2, in the waveform grid 1 of the present embodiment, each waveform element 2 and each fuel pin 101 are in line contact with each other. FIG. 2B shows the configuration of the connection plate 4 that connects the corrugated grid 1. The connection plate 4 has a strip shape, and is configured such that the two grooves formed in the connection plate 4 are engaged with the grooves of the wave element 2 to be connected.

  3 to 6 show other support structures of the fuel pin 101 by the wave element 2. In this configuration example, the dimple 6 is provided on the wave element 2 so that the wave element 2 and the fuel pin 101 are in point contact. In this example, the dimple 6 has a hemispherical shape with a predetermined radius R. Note that the present invention is not limited to this shape, and various modifications are possible as long as the dimples are formed by curved projections.

  7 to 9 show other configuration examples having different configurations. In this example, the dimple is configured as an arch dimple 7 so that the corrugated element 2 and the fuel pin 101 are in line contact with a small contact surface. The arch dimple 7 is described as a semi-cylindrical shape having a radius R, but is not limited to this shape, and includes a dimple formed by a protruding portion of a curved surface.

  10 to 12 show other configuration examples having different configurations. In this example, the corrugated element 2 and the fuel pin 101 are configured as a notched dimple 8 so as to have a line contact with a small contact surface. The notch type dimple 8 is configured to press the fuel pin 101 by utilizing the spring property of the steel material. In FIG. 11, the notched dimple 8 is shown as a semi-cylindrical shape having a radius R. However, the present invention is not limited to this shape, and the dimple 8 may be implemented as a dimple having various shapes formed by curved protrusions. Can do.

[Second Embodiment (FIG. 13)]
FIGS. 13A, 13B, and 13C are explanatory views showing the configuration of the second embodiment. As shown in these drawings, in the present embodiment, a corrugated element 2 for storing and holding a plurality of fuel pins 101 in a trumpet tube 103 at equal intervals, and a grid in which a connecting plate 4 is fixed to a grid frame 112 are corrugated elements. By rotating the direction of 2 by 60 ° and overlapping the two pieces, a single-stage grid is formed. According to such a configuration, since the corrugated element 2 does not overlap in the vertical direction and a uniform flow is obtained, the grid pressure loss can be reduced and the structural strength can be improved. Therefore, a nuclear fuel assembly having a low pressure loss can be provided. Three or more stages may be used.

  FIGS. 14A, 14 </ b> B, 14 </ b> C, 14 </ b> D, and 14 </ b> E are explanatory diagrams illustrating another configuration example of the present embodiment. As shown in these drawings, in this configuration example, a pair of upper and lower corrugated elements 2 are stacked at different angles of 60 ° on a plane as shown in FIG. It is the structure joined by welding so that 13 may overlap. Even in such a configuration, the combination of the upper corrugated element 11 and the lower corrugated element 12 can reduce the pressure loss of the grid and improve the structural strength.

[Third Embodiment (FIGS. 15 to 17)]
FIG. 15 is a cross-sectional view showing a third embodiment of the nuclear fuel assembly, and FIG. 16 is an enlarged cross-sectional view showing one grid portion of the nuclear fuel assembly shown in FIG. FIG. 17 is an enlarged cross-sectional view showing another grid portion that is vertically adjacent to the grid portion shown in FIG.

  In the present embodiment, as shown in FIG. 16, the wave element 2 is arranged in the horizontal direction shown in the figure, and as shown in FIG. 17, the wave element 2 is rotated by 60 ° with respect to that in FIG. Those to be arranged are alternately installed in the vertical direction of the fuel assembly. That is, a grid is formed by fixing the corrugated element 2 and the connecting plate 4 which are accommodated and held in the trumpet tube 103 at equal intervals in the trumpet tube 103 to the grid frame 112, and a plurality of stages are maintained while keeping the axial interval. It is set as the structure which rotated the direction of the grid waveform element 2 which adjoins the pin bundle which consists of this grid to a different direction (60 degree rotation etc.). As a result, the nuclear fuel assembly can reduce pressure loss and improve the structural strength. In the illustrated example, the rotation is performed by 60 °. However, for example, the direction of adjacent grids may be changed by changing 60 °..., 120 °.

[Fourth Embodiment (FIGS. 18 to 23)]
18 is a cross-sectional view showing a fourth embodiment of a nuclear fuel assembly according to the present invention, and FIG. 19 is a partially enlarged view of FIG. As shown in these drawings, in the present embodiment, a plurality of fuel pins 10 are basically configured by a grid in which ring elements 14 that are accommodated and held at equal intervals in the trumpet tube 103 are fixed to a grid frame 112. In this configuration, the ring element 14 is configured as a partial grid in which only a few rows are arranged from the grid frame 112. According to such a configuration, since only the fuel pins 101 near the outer periphery are supported by the grid, the distance between the fuel pins 101 near the outer periphery where the curvature of the fuel pin 101 is large can be reliably maintained, while the center side arrangement Since the flow resistance of the coolant is reduced in the fuel pin 101, a nuclear fuel assembly with a low pressure loss can be obtained. In the axial direction of the nuclear fuel assembly, particularly in the vicinity of the core portion where the curvature of the fuel pin 101 is large, such a grid is adopted, and in the lower portion and the upper portion in the axial direction, a grid having the ring element 14 at the center is used. The spacing of the fuel pins 101 can be maintained at each cross section over the top.

  FIG. 20 shows a modification of the present embodiment. In this configuration example, the grid elements 112 are constituted by partial grids in which honeycomb elements 15 are arranged in only a few rows. According to such a configuration, it is possible to reliably maintain the distance between the fuel pins 101 in the vicinity of the outer periphery where the curvature of the fuel pins 101 is large and to provide a nuclear fuel assembly with low pressure loss.

  FIG. 21 shows still another configuration example of the present embodiment. In this configuration example, only a few columns from the grid frame 112 are configured by partial grids in which the waveform elements 2 are arranged. According to such a configuration, it is possible to reliably maintain the distance between the fuel pins 101 in the vicinity of the outer periphery where the curvature of the fuel pins 101 is large and to provide a nuclear fuel assembly with low pressure loss.

FIG. 22 shows another configuration example of the present embodiment. FIG. 23 is an enlarged view of a main part of FIG. As shown in these figures, in this configuration example, the grid elements 112 are configured by partial grids in which the ring elements 14 are arranged only from the lower part of the grid frame 112. In particular, it is possible to reliably maintain the distance between the fuel pins 101 near the outer periphery where the curvature of the fuel pins 101 is large, and to provide a nuclear fuel assembly with low pressure loss. In the illustrated example, a configuration example of the ring element 14 is shown. However, the ring element 14 or the corrugated element 2 may be used. Even in the case of such a configuration, the same effect as described above is obtained.

[Fifth Embodiment (FIGS. 24 and 25)]
FIG. 24 is a schematic plan view showing the fifth embodiment of the present invention.

  As shown in FIG. 24, in this embodiment, in a grid in which a ring element 14 for storing and holding a plurality of fuel pins 101 at equal intervals in a trumpet tube 103 is fixed to a grid frame 112, the ring element 14 is a grid. Only a few rows are arranged from the frame 112, and a grid composed of corrugated elements 2 is arranged on the inner side thereof. In particular, a fuel pin 101 interval near the outer periphery with a large curve of the fuel pin 101 is maintained to provide a nuclear fuel assembly with low pressure loss. Can do.

  FIG. 25 shows another configuration example. In this example, the grid is divided into a grid 1 region G1 and a grid 2 region G2, and the grid 1 region G1 and the grid 2 region G2 are configured by different elements. The grid 1 region G1 is composed of a ring element 14 having a high element strength, a honeycomb element 15 and the like, and the grid 2 region G2 in the center is composed of a wave element 2 and a rhombus element. Such a configuration can also provide a nuclear fuel assembly with low pressure loss.

[Sixth Embodiment (FIGS. 26 and 27)]
FIG. 26 shows a sixth embodiment of the present invention.

  In the present embodiment, a grid is formed by the chevron elements 15 that store and hold a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals, and the connection plate 4 to reduce the pressure loss of the grid. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

  FIG. 27 shows another configuration example. In this example, it is possible to reduce the pressure loss of the grid by forming a grid with the chevron elements 15 processed with the dimples 6 that store and hold the plurality of fuel pins 101 in the trumpet tube 103 at equal intervals and the connection plate 4. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

[Seventh Embodiment (FIGS. 28 to 31)]
28 to 30 show a seventh embodiment of the present invention.

  As shown in these drawings, in the present embodiment, the notched corrugated element 16 and the connecting plate 4 in which a part of a plate for storing and holding a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals are cut out. A grid fixed to the grid frame can be configured to reduce the grid pressure loss. Moreover, since there is the notch portion 17, the amount of material can be reduced. Any notch shape may be used.

  FIG. 31 shows another configuration example. In this example, a grid in which a porous corrugated element 18 in which a part of a plate for storing and holding a plurality of fuel pins 101 at equal intervals in a trumpet tube 103 is cut into a circular porous shape and a connection plate 4 are fixed to a grid frame is provided. It has a structured structure. Thereby, the pressure loss reduction of a grid can be aimed at. Moreover, since there is the notch part 17, a quantity reduction can be aimed at.

[Eighth Embodiment (FIGS. 32 to 38)]
32 to 34 show an eighth embodiment of the present invention.

  As shown in these drawings, in this embodiment, a protrusion is formed in which a continuous protrusion 21 is provided in a length direction on a part of a plate for storing and holding a plurality of fuel pins 101 in a trumpet tube 103 at equal intervals. A grid in which the corrugated element 20 and the connection plate 4 are fixed to a grid frame is formed, and the strength of the grid can be improved and the pressure loss can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

  FIG. 35 and FIG. 36 show other configuration examples with different processing methods. In this example, the projection forming wave element 20 and the connection plate 4 in which two continuous projections 21 are provided in the length direction on a part of a plate for storing and holding a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals. The grid is fixed to the grid frame to improve the strength of the grid and reduce the pressure loss. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

  FIG. 37 and FIG. 38 show other configuration examples having different processing methods. In this example, a protrusion forming waveform in which a plurality of continuous protrusions 21 are provided in the length direction on a part of a plate for storing and holding a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals. A grid in which the element 20 and the connection plate 4 are fixed to the grid frame can be formed, and the strength of the grid can be improved and the pressure loss can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

[Ninth Embodiment (FIGS. 39 to 46)]
39 and 40 show a ninth embodiment of the present invention.

  As shown in these drawings, in this embodiment, in the grid in which the corrugated element 2 and the connecting plate 4 that store and hold the plurality of fuel pins 101 in the trumpet tube 103 at equal intervals are fixed to the peripheral waveform. The peripheral obstruction 22 can be provided between the element and the grid frame 112 to prevent the peripheral flow effect of the coolant and to improve the thermal efficiency. In addition, the pressure loss can be reduced while improving the strength of the grid.

  41 and 42 show other configuration examples with different processing methods. In this example, in a grid in which a plurality of fuel pins 101 are accommodated and held in a trumpet tube 103 at equal intervals and a connecting plate 4 is fixed to the grid frame 112, the gap between the peripheral waveform elements 2 and the grid frame 112 is fixed. A long peripheral obstruction 23 can be provided to prevent the peripheral flow effect of the coolant and improve the thermal efficiency. In addition, the pressure loss can be reduced while improving the strength of the grid.

  FIG. 43 and FIG. 44 illustrate another configuration example with a different processing method. In this example, in the grid in which the corrugated element 2 and the connecting plate 4 that store and hold a plurality of fuel pins 101 at equal intervals in the trumpet tube 103 are fixed to the grid frame 112, the upper and lower ends of the surrounding grid frame 112 are the fuel pins. The obstruction baffle plate 24 bent to the 101 side can be processed to prevent the peripheral flow effect of the coolant and to improve the thermal efficiency. In addition, the pressure loss can be reduced while improving the strength of the grid.

  45 and 46 show other configuration examples with different processing methods. In this example, in a grid in which a plurality of fuel pins 101 are accommodated and held in a trumpet tube 103 at equal intervals and a connecting plate 4 is fixed to a grid frame 112, the upper and lower ends of the outer peripheral waveform element 2 are grid frames. The blocking baffle plate 25 bent to the 112 side can be processed to prevent the peripheral flow effect of the coolant and to improve the thermal efficiency. In addition, the pressure loss can be reduced while improving the strength of the grid.

[Tenth Embodiment (FIGS. 47 to 56)]
47 to 49 show a tenth embodiment of the present invention.

  As shown in these drawings, in this embodiment, a plurality of fuel pins 101 are stored and held in the trumpet tube 103 at equal intervals, and a plurality of peripheral blockages having a mountain-like cross section around the periphery, for example, a triangular shape. Peripheral blockage structures 28 composed of rods 26 and regular hexagonal peripheral frames 27 that support these peripheral rods are alternately incorporated into a plurality of stages to prevent the peripheral flow effect of the coolant and improve the thermal efficiency.

  Moreover, the axial position of the grid can be positioned by the peripheral closing structure 28, and the efficiency reduction of placing the tie rod 5 that is not fuel in the assembly can be prevented. Further, the grid and the peripheral obstruction structure 28 can be easily assembled in the trumpet tube 103, and the strength can be improved.

  50 and 51 show other configuration examples having different configurations of the peripheral obstruction structure. In this example, a grid for storing and holding a plurality of fuel pins 101 at equal intervals in a trumpet tube 103, and a peripheral closing structure 28 comprising a semicircular closing rod 29 having a semicircular cross section and a peripheral frame 27 are alternately arranged. Multiple stages can be incorporated to prevent the peripheral flow effect of the coolant and improve the thermal efficiency. Moreover, the axial position of the grid can be positioned by the peripheral closing structure 28, and the efficiency reduction of placing the tie rod 5 that is not fuel in the assembly can be prevented. Furthermore, the grid and the peripheral obstruction structure 28 can be easily assembled in the trumpet tube 103, and the strength can be improved.

  FIG. 51 shows another configuration example in which the circular peripheral blocking rod 30 is configured as the peripheral blocking object structure 27.

  FIG. 52 is another configuration example in which the configuration of the peripheral obstruction structure is different. A grid for storing and holding a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals, and a peripheral blocking structure 28 including a hollow blocking rod 32 and a peripheral frame 27 are alternately incorporated in a plurality of stages in the assembly so that the coolant The peripheral flow effect can be prevented and the thermal efficiency can be improved.

  Moreover, the axial position of the grid can be positioned by the peripheral closing structure 28, and the efficiency reduction of placing the tie rod 5 which is not fuel in the assembly can be prevented. Further, the grid and the peripheral obstruction structure 28 can be easily assembled in the trumpet tube 103, and the strength can be improved.

  53 and 54 show another configuration example in which the labyrinth block rod 33 is configured as the peripheral blockage structure 28. FIG.

  As shown in these figures, the flow resistance of the labyrinth 34 can further prevent the peripheral flow effect of the coolant and improve the thermal efficiency. FIG. 55 and FIG. 56 show another configuration example in which the spiral blocking rod 35 is configured as the peripheral blocking object structure 28. The flow resistance of the spiral blades 36 can further prevent the peripheral flow effect of the coolant and improve the thermal efficiency.

[Eleventh Embodiment (FIGS. 57 to 62)]
57 and 58 show an eleventh embodiment of the present invention.

  As shown in these drawings, in this embodiment, the fuel cell 101 is configured by a grid in which a hollow cell 37 for storing and holding a plurality of fuel pins 101 at equal intervals in a trumpet tube 103 and a connection plate 38 are fixed to a grid frame 112. It is possible to reduce the pressure loss while improving the strength of the grid.

  59 and 60 show other configuration examples. In this example, a triangular hollow cell 39 for storing and holding a plurality of fuel pins 101 in a trumpet tube 103 at equal intervals and a grid in which a connection plate 38 is fixed to a grid frame 112 are improved. Can be achieved.

  61 and 62 show still another configuration example. In this example, a triangular rod 40 for storing and holding a plurality of fuel pins 101 in a trumpet tube 103 at equal intervals and a grid in which a connecting plate 38 is fixed to a grid frame 112 are improved, and the pressure loss is reduced while improving the strength of the grid. Can be planned.

[Twelfth Embodiment (FIGS. 63 to 66)]
FIG. 63 is a cross-sectional view showing a twelfth embodiment of the present invention, and FIG. 64 is an enlarged cross-sectional view showing the structure of the obstruction around the upper and lower ends of the nuclear fuel assembly shown in FIG. FIG. 65 is an enlarged cross-sectional view showing the structure of the obstruction in the upper and lower intermediate regions of the nuclear fuel assembly of FIG. 66 is a diagram showing Table 1. FIG.

  As shown in FIGS. 63 to 65, in this embodiment, a waveform grid 1 in which a waveform element 2 for storing and holding a plurality of fuel pins 101 at equal intervals in a trumpet tube 103 and a connection plate 4 are fixed to a grid frame 112. Are arranged in a plurality of stages at the upper and lower stages of the pin bundle part, and a plurality of high-strength honeycomb grids 41 are provided at the axially intermediate part (core part) where the fuel pin 101 is largely bent. Since the interval between the fuel pins 101 at the axially intermediate portion where the fuel pin 101 is greatly curved can be reliably maintained and the coolant flow path can be secured, the soundness of the nuclear fuel assembly can be improved. FIG. 63 shows a configuration example in which a grid suitable for each of the grid areas GA1, GA2, and GA3 is incorporated.

  Table 1 is an example of grid arrangement suitable for each of the grid areas GA1, GA2, and GA3. Basically, this is a configuration example in which a high-strength grid is arranged in an axially intermediate portion (core portion) where the fuel pin 101 is greatly curved and deformed. As in configuration examples 2, 3, and 4, a plurality of stages are arranged in the upper and lower stages of the pin bundle part, and a plurality of high-strength grids are provided in the axially intermediate part (core part) where the fuel pin 101 is greatly deformed. Structure. By adopting such a configuration, it is possible to reliably hold the fuel pin 101 interval in the axially intermediate portion where the curved deformation of the fuel pin 101 is large, and to secure the coolant flow path. Can be improved.

[Thirteenth Embodiment (FIGS. 67 to 69)]
FIG. 67 is a cross-sectional view showing a thirteenth embodiment of the present invention, and FIG. 68 is an explanatory view showing an enlarged fuel pin in FIG. As shown in these drawings, in the present embodiment, a plurality of grids for storing and holding a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals are arranged on the upper and lower stages of the pin bundle portion. Further, a partial wire pin composed of a spirally wound wire 44 is provided from the middle lower end plug 45 to the middle upper end plug 46 at the axially middle portion of the fuel pin 101 where the thermal bending deformation is large. According to such a configuration, it is possible to reliably maintain the fuel pin interval in the axially intermediate portion where the bending deformation of the pin is large and to secure the coolant flow path, thereby improving the soundness of the nuclear fuel assembly. it can.

  FIGS. 69A and 69B show another configuration example in which a partial wire is configured. A grid for storing and holding a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals is arranged in a plurality of stages at the upper stage or the lower stage of the pin bundle part, and the lower part including the axially intermediate part where the thermal bending deformation of the fuel pin 101 is large or In the upper part, a partial wire pin composed of a wire 44 spirally wound from the intermediate end plug 49 to the one end plug is provided, and the fuel pin interval in the axially intermediate portion where the bending deformation of the pin is large is reliably maintained and the coolant A flow path can be secured. By adopting such a configuration, the soundness of the nuclear fuel assembly can be improved.

[Fourteenth Embodiment (FIGS. 70 to 79)]
FIG. 70 shows a configuration in which a honeycomb grid 41 storing and holding a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals is processed by cutting the honeycomb grid 41 from the block by wire cutting. Specifically, for example, as shown in FIG. 71, the honeycomb element 43 can be welded. In this case, the thickness is 2 to 2 times the wall thickness t.

  On the other hand, as shown in FIG. 72, it is possible to leave the wall thickness t by performing processing by wire cutting. In this configuration, the blocking rate ε is reduced, and the pressure loss can be reduced. Therefore, also in this embodiment, a nuclear fuel assembly having a low pressure loss can be provided.

  73 to 76 show other configuration examples processed by wire cutting. In the honeycomb grid 41 in which a plurality of fuel pins 101 are stored and held in the trumpet tube 103 at equal intervals, the honeycomb grid 41 is cut from the block by wire cutting and manufactured. The present embodiment is characterized in that the long dimple 52 or the dimple 53 is left. The dimple 53 can be processed by cutting the upper and lower portions with an end mill after processing the long dimple 52. The fuel pin 101 can be reliably held for the dimple. Further, the blocking rate ε is reduced, and the pressure loss can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

  FIG. 77 is characterized in that a ring grid in which a plurality of fuel pins 101 are stored and held in the trumpet tube 103 at equal intervals is manufactured by cutting the ring grid from the block by wire cutting. The dimple 53 is also processed by leaving a wire cut. In FIG. 78, when the ring element 14 is constructed by welding, the plate thickness is twice 2t of the wall thickness t. However, the wire cut in FIG. 79 can leave the wall thickness t. For this reason, the blocking rate ε is reduced, and the pressure loss can be reduced. Therefore, a nuclear fuel assembly having a low pressure loss can be provided.

[Fifteenth embodiment (corresponding to claim 15, FIGS. 80 to 85)]
FIGS. 80 to 83 show a peripheral flow between a peripheral fuel pin 101 and a wrapper tube 103 in a fuel pin bundle composed of a grid 102 that stores and holds a plurality of fuel pins 101 in the wrapper tube 103 at equal intervals. In order to prevent the effect, the triangular fuel pin 54 is also provided as a peripheral obstruction, and in addition to preventing the peripheral flow effect of the coolant, the triangular fuel pin is arranged in the periphery. With such a configuration, the thermal efficiency can be further improved.

  FIG. 84 shows another configuration example of the present embodiment. In a fuel pin bundle composed of a grid 102 that accommodates and holds a plurality of fuel pins 101 in a trumpet tube 103 at equal intervals, in order to prevent a peripheral flow effect between the surrounding fuel pins 101 and the trumpet tube 103, A fuel pin 56 is also provided as a peripheral blockage to prevent the peripheral flow effect of the coolant. In addition to this, the thermal efficiency can be further improved by arranging the angle fuel pin 56 around the periphery.

  FIG. 85 shows still another configuration example. This configuration example is also based on a fuel pin bundle composed of a grid 102 that stores and holds a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals. In order to prevent the peripheral flow effect between the peripheral fuel pin 101 and the trumpet tube 103, a small-diameter fuel pin 57 is also provided as a peripheral blockage to prevent the peripheral flow effect of the coolant. In addition to this, the thermal efficiency can be further improved by arranging the angle fuel pin 57 around the periphery.

[Sixteenth Embodiment (FIGS. 86 to 91)]
86 to 88 show that the grid frame 112 is welded and fixed to the trumpet tube 103 in a fuel pin bundle composed of a grid 102 that stores and holds a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals. 88, a welding electrode is installed on the inner side of the grid frame 112 and the outer side of the trumpet tube 103 and fixed by welding before the fuel pin 101 is assembled in FIG. The position of the grid in the axial direction can be securely fixed, and the integrity of the nuclear fuel assembly can be improved.

  89 and 90 show other configuration examples. 89. In a fuel pin bundle composed of a grid 102 that stores and holds a plurality of fuel pins 101 in a trumpet tube 103 at equal intervals, the grid frame 112 is welded and fixed to the trumpet tube 103. In FIG. Before assembling the pins 101, welding electrodes are installed and fixed on the inside of the grid frame 112 and the outside of the trumpet tube 103. There is a configuration example in which a welding ear 59 is provided in consideration of ease of welding. The position of the grid in the axial direction can be securely fixed, and the integrity of the nuclear fuel assembly can be improved.

  FIG. 91 shows another configuration example. 91. In a fuel pin bundle composed of a grid 102 for storing and holding a plurality of fuel pins 101 in a trumpet tube 103 at equal intervals, the grid frame 112 is fixed to the trumpet tube 103 by welding. Before assembling the pins 101, the grid frame 112 and the fixing screw 60 for fixing the trumpet tube 103 are fixed, and the head of the fixing screw 60 is fixed from the outside of the trumpet tube by sealing welding. The position of the grid in the axial direction can be securely fixed, and the integrity of the nuclear fuel assembly can be improved.

[Seventeenth Embodiment (FIGS. 92 to 96)]
FIGS. 92A and 92B are cross-sectional views showing a seventeenth embodiment of the present invention, in which FIG. 92A is an enlarged view of a main part, and FIG. 92B is an enlarged view showing a connection plate of FIG. FIG. 93 is an enlarged cross-sectional view illustrating an edge shape. In this embodiment, as shown in FIGS. 92 (a) and 92 (b), the corrugated element 2 and the connecting plate 4 for storing and holding a plurality of fuel pins 101 in the trumpet tube 103 at equal intervals are provided in the grid frame 112. It is configured based on a fixed grid.

  In such a configuration, as shown in FIG. 93, triangular edges 61 are respectively formed at the upper and lower edges of the wave element 2. Similarly, triangular edges 61 are also formed on the upper and lower edges of the connection plate 4. According to such a configuration, the flow resistance of the coolant to the corrugated element 2 and the connection plate 4 is reduced by forming the triangular edge 61. Accordingly, the pressure loss of the grid can be reduced, and thus a nuclear fuel assembly with a low pressure loss can be provided.

  94, 95, and 96 are enlarged cross-sectional views illustrating other edge shapes in the present embodiment, respectively. FIG. 94 shows a configuration example formed as a trapezoidal edge 62 with the edge tip removed. FIG. 95 shows a configuration example in which the streamlined edge 63 is processed with the edge as a curved surface. Further, FIG. 96 shows a configuration example in which the one-side edge 64 is processed.

  By adopting such an edge configuration of each shape, the pressure loss of the grid can be reduced as described above, and a nuclear fuel assembly having a low pressure loss can be provided.

1 is a cross-sectional view showing a first embodiment of a nuclear fuel assembly according to the present invention. (A) is a principal part enlarged view of FIG. 1, (b) is an enlarged view which shows the connection board of (a). The top view which shows the other structural example of 1st Embodiment. The principal part enlarged view of FIG. The side view of FIG. The other sectional side view of FIG. The side view which shows the other structural example of 1st Embodiment. FIG. 8 is a plan sectional view of FIG. 7. FIG. 8 is a side sectional view of FIG. 7. The side view which shows the other structural example of 1st Embodiment. FIG. 11 is a plan sectional view of FIG. 10. FIG. 11 is a side sectional view of FIG. 10. (A), (b), (c) is explanatory drawing which shows 2nd Embodiment of this invention. (A), (b), (c), (d), (e) is explanatory drawing which shows the other structural example of 2nd Embodiment. The cross-sectional view showing a third embodiment of the nuclear fuel assembly according to the present invention. FIG. 16 is an enlarged cross-sectional view showing one grid portion of the nuclear fuel assembly shown in FIG. 15. The expanded cross-sectional view which shows the other grid part adjacent to the grid part shown in FIG. 16 up and down. The cross-sectional view showing a fourth embodiment of a nuclear fuel assembly according to the present invention. The elements on larger scale of FIG. The figure which shows the modification of 4th Embodiment. The schematic plan view which shows the other structural example of 4th Embodiment. The schematic plan view which shows the further another structural example of 4th Embodiment. The principal part enlarged view of FIG. The schematic plan view which shows the other structural example of 5th Embodiment of the nuclear fuel assembly which concerns on this invention. Explanatory drawing of 5th Embodiment. The expanded top view which shows 6th Embodiment of the nuclear fuel assembly which concerns on this invention. The enlarged plan view which shows the other structural example of 6th Embodiment. The schematic plan view which shows 7th Embodiment of the nuclear fuel assembly which concerns on this invention. The top view which shows the waveform element of FIG. The side view of FIG. Explanatory drawing which shows the other structural example of 7th Embodiment. The schematic plan view which shows 8th Embodiment of the nuclear fuel assembly which concerns on this invention. The side view of FIG. FIG. 33 is a side sectional view from a different direction of FIG. 32. The side view which shows the other structural example of 8th Embodiment. FIG. 36 is a side sectional view from a different direction of FIG. 35. The side view which shows the other structural example of 8th Embodiment. FIG. 38 is a side sectional view from a different direction of FIG. 37. A cross-sectional view showing a ninth embodiment of a nuclear fuel assembly according to the present invention. FIG. 40 is a sectional view taken along line B-B in FIG. 39. The cross-sectional view showing another configuration example of the ninth embodiment. B1-B1 sectional view taken on the line of FIG. The cross-sectional view showing another configuration example of the ninth embodiment. B2-B2 sectional view taken on the line of FIG. The cross-sectional view showing another configuration example of the ninth embodiment. FIG. 46 is a sectional view taken along line B3-B3 of FIG. The whole sectional view showing a 10th embodiment of the nuclear fuel assembly concerning the present invention. The cross-sectional enlarged view of FIG. The CC sectional view taken on the line of FIG. Sectional drawing which shows the other structural example of 10 embodiment. Sectional drawing which shows the other structural example of 10 embodiment. Sectional drawing which shows the other structural example of 10 embodiment. Sectional drawing which shows the other structural example of 10 embodiment. The side view of FIG. Sectional drawing which shows the other structural example of 10 embodiment. The side view of FIG. A cross-sectional view showing an eleventh embodiment of a nuclear fuel assembly according to the present invention. FIG. 58 is a sectional view taken along line D1-D1 of FIG. Sectional drawing which shows the other structural example of 11th Embodiment. FIG. 60 is a sectional view taken along line D2-D2 of FIG. 59. Sectional drawing which shows the other structural example of 11th Embodiment. FIG. 62 is a sectional view taken along line D3-D3 of FIG. 61. A cross-sectional view showing a twelfth embodiment of a nuclear fuel assembly according to the present invention. FIG. 64 is an enlarged cross-sectional view showing a configuration of an obstruction around the upper and lower ends of the nuclear fuel assembly in FIG. 63. FIG. 64 is an enlarged cross-sectional view showing the structure of the obstruction in the upper and lower intermediate regions of the nuclear fuel assembly of FIG. 63. FIG. A cross-sectional view showing a thirteenth embodiment of a nuclear fuel assembly according to the present invention. FIG. 68 is an explanatory diagram showing the fuel pin in FIG. 67 in an enlarged manner. (A), (b) is explanatory drawing which shows the other structural example of 13th Embodiment. A cross-sectional view showing a fourteenth embodiment of a nuclear fuel assembly according to the present invention. Schematic which shows the other structural example of 14th Embodiment. Schematic which shows the other structural example of 14th Embodiment. Schematic which shows the other structural example of 14th Embodiment. Schematic which shows the other structural example of 14th Embodiment. Schematic which shows the other structural example of 14th Embodiment. Schematic which shows the other structural example of 14th Embodiment. Schematic which shows the other structural example of 14th Embodiment. Schematic which shows the other structural example of 14th Embodiment. Schematic which shows the other structural example of 14th Embodiment. A cross-sectional view showing a fifteenth embodiment of a nuclear fuel assembly according to the present invention. FIG. 81 is an enlarged cross-sectional view of FIG. The principal part enlarged view of FIG. The top view of FIG. Schematic which shows the other structural example of 15th Embodiment. Schematic which shows the other structural example of 15th Embodiment. A cross-sectional view showing a sixteenth embodiment of a nuclear fuel assembly according to the present invention. FIG. 89 is an enlarged cross-sectional view taken along line AA in FIG. 86. FIG. 88 is a side sectional view of FIG. 87. Schematic which shows the other structural example of 16th Embodiment. The side view of FIG. Schematic which shows the other structural example of 16th Embodiment. It is a cross-sectional view which shows 17th Embodiment of the nuclear fuel assembly which concerns on this invention, (a) is a principal part enlarged view, (b) is an enlarged view which shows the connection board of (a). The expanded sectional view which illustrates the edge shape in a 17th embodiment. The expanded sectional view which illustrates other edge shape in a 17th embodiment. The expanded sectional view which illustrates other edge shape in a 17th embodiment. The expanded sectional view which illustrates other edge shape in a 17th embodiment. FIG. 6 is a schematic longitudinal sectional view showing a conventional nuclear fuel assembly. FIG. 6 is a schematic vertical plan view showing a conventional nuclear fuel assembly. The enlarged plan view which shows the grid of the conventional nuclear fuel assembly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Waveform grid, 2 ... Waveform element, 4 ... Connection board, 5 ... Tie rod, 6 ... Dimple, 7 ... Arch type dimple, 8 ... Notch type dimple, 9 ... Upper grid frame, 10 ... Lower grid frame, 11 ... Upper corrugated element, 12 ... Lower corrugated element, 13 ... Notch combination part, 14 ... Ring element, 15 ... Honeycomb element, 16 ... Notch corrugated element, 17 ... Notch part, 18 ... Porous corrugated element, 19 ... Porous , 20 ... Projection forming wave element, 21 ... Continuous projection, 22 ... Peripheral obstruction, 23 ... Long peripheral obstruction, 24 ... Obstruction baffle, 25 ... Obstruction baffle, 26 ... Peripheral obstruction rod, 27 ... Peripheral Frame: 28 ... Peripheral occlusion structure, 29 ... Semicircular peripheral occlusion rod, 30 ... Circular peripheral occlusion rod, 31 ... Corrugated peripheral occlusion rod, 32 ... Hollow occlusion rod, 33 ... Labyrinth occlusion rod, 34 ... Labyrinth, 3 ... Spiral occlusion Stick, 36 ... let Blades, 37 ... hollow cells, 38 ... connecting plate, 39 ... triangular hollow cell, 40 ... triangular rod, 41 ... honeycomb grid, 42 ... peripheral obstruction, 43 ... honeycomb element, 4 ... wire, 45 ... middle lower end plug, 46 ... Middle upper end plug, 47 ... Lower end plug, 48 ... Upper end plug, 49 ... Middle end plug, 50 ... Welded part, 51 ... Cut-off part, 52 ... Long dimple, 53 ... Dimple, 54 ... Triangular fuel pin, 55 ... Fuel pellet, 56 ... Angle fuel pin, 57 ... Small diameter fuel pin, 58 ... Frame fixing welding, 59 ... Ear for welding, 60 ... Fixing screw, 61 ... Triangular edge, 62 ... Trapezoid edge, 63 ... Streamline edge, 64: One side edge, 101: Fuel pin, 102 ... Grid, 103 ... Trumpet tube, 104 ... Entrance nozzle, 105 ... Lower pin support plate, 106 ... Upper pin support plate, 107 ... Handling head, 08 ... coolant inlet, 109 ... coolant outlet, 110 ... Rhombus grid, 111 ... Rhombus element, 112 ... grid cell.

Claims (8)

A nuclear fuel assembly loaded into the core of a nuclear reactor with a liquid metal coolant,
A plurality of corrugated elements having a corrugated shape curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly , and storing and holding a plurality of fuel pins at equal intervals in a trumpet tube ,
A connecting plate having two grooves, and connecting the corrugated elements by engaging the corrugated elements with the grooves,
A plurality of grids in which the corrugated element and the connection plate are fixed to a grid frame;
An entrance nozzle,
A handling head,
Each said corrugated element supports the said fuel pin by two point contacts or two line contacts on the horizontal cross section of the said nuclear fuel assembly, The nuclear fuel assembly characterized by the above-mentioned. A nuclear fuel assembly loaded into the core of a nuclear reactor with a liquid metal coolant,
A plurality of corrugated elements having a corrugated shape curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly , and storing and holding a plurality of fuel pins at equal intervals in a trumpet tube ,
A connecting plate having two grooves, and connecting the corrugated elements by engaging the corrugated elements with the grooves,
A multistage grid in which two grids each having a waveform element and the connection plate fixed to a grid frame and rotated in the direction of the waveform element by 60 ° are stacked;
An entrance nozzle,
A handling head,
A plurality of the multistage grids;
Each said corrugated element supports the said fuel pin by two point contacts or two line contacts on the horizontal cross section of the said nuclear fuel assembly, The nuclear fuel assembly characterized by the above-mentioned. A nuclear fuel assembly loaded into the core of a nuclear reactor with a liquid metal coolant,
A plurality of corrugated elements having a corrugated shape curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly , and storing and holding a plurality of fuel pins at equal intervals in a trumpet tube ,
A connecting plate having two grooves, and connecting the corrugated elements by engaging the corrugated elements with the grooves,
A grid in which the corrugated element and the connection plate are fixed to a grid frame is configured as a multi-stage grid with a gap in the axial direction, and a plurality of stages in which the directions of the grid corrugated elements adjacent in the axial direction are rotated in different directions. The grid;
An entrance nozzle,
A handling head,
Each said corrugated element supports the said fuel pin by two point contacts or two line contacts on the horizontal cross section of the said nuclear fuel assembly, The nuclear fuel assembly characterized by the above-mentioned. A nuclear fuel assembly loaded into the core of a nuclear reactor with a liquid metal coolant,
A plurality of chevron elements having a chevron shape bent in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly , and storing and holding a plurality of fuel pins in a trumpet at equal intervals;
A connecting plate having two grooves, and connecting the chevron elements by engaging the chevron elements in the grooves;
A plurality of grids in which the chevron element and the connection plate are fixed to a grid frame;
An entrance nozzle,
A handling head,
Each said chevron element supports the said fuel pin by two point contacts or two line contacts on the horizontal cross section of the said nuclear fuel assembly, The nuclear fuel assembly characterized by the above-mentioned. A nuclear fuel assembly loaded into the core of a nuclear reactor with a liquid metal coolant,
A plurality of corrugated elements having a corrugated shape curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly , and storing and holding a plurality of fuel pins at equal intervals in a trumpet tube ,
A notch provided on an axially horizontal surface of the nuclear fuel assembly of the wave element;
A connecting plate having two grooves, and connecting the corrugated elements by engaging the corrugated elements with the grooves,
A plurality of grids in which a front wave waveform element and the connection plate are fixed to a grid frame;
An entrance nozzle,
A handling head,
Each said corrugated element supports the said fuel pin by two point contacts or two line contacts on the horizontal cross section of the said nuclear fuel assembly, The nuclear fuel assembly characterized by the above-mentioned. A nuclear fuel assembly loaded into the core of a nuclear reactor with a liquid metal coolant,
A part of a plate that has a corrugated shape that is curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly, and that accommodates and holds a plurality of fuel pins at equal intervals in a trumpet tube A plurality of corrugated elements provided with continuous protrusions along the horizontal direction ;
A connecting plate having two grooves, and connecting the corrugated elements by engaging the corrugated elements with the grooves,
A plurality of grids in which the corrugated element and the connection plate are fixed to a grid frame;
An entrance nozzle,
A handling head,
Each said corrugated element supports the said fuel pin by two point contacts or two line contacts on the horizontal cross section of the said nuclear fuel assembly, The nuclear fuel assembly characterized by the above-mentioned. A nuclear fuel assembly loaded into the core of a nuclear reactor with a liquid metal coolant,
A plurality of corrugated elements having a corrugated shape curved in alternate directions at predetermined distances on a cross section perpendicular to the axial direction of the nuclear fuel assembly , and storing and holding a plurality of fuel pins at equal intervals in a trumpet tube ,
A connecting plate having two grooves, and connecting the corrugated elements by engaging the corrugated elements with the grooves,
A plurality of grids in which the corrugated element and the connection plate are fixed to a grid frame;
An entrance nozzle,
A handling head,
Each of the corrugated element and the connecting plate is processed into a triangular edge at the upper and lower ends,
Each said corrugated element supports the said fuel pin by two point contacts or two line contacts on the horizontal cross section of the said nuclear fuel assembly, The nuclear fuel assembly characterized by the above-mentioned. The nuclear fuel assembly according to any one of claims 1 to 7, wherein a pitch P of the fuel pins and an outer diameter D of the fuel pins satisfy 1 <P / D <1.154.

Images